libv4l: Improved pac207 decompression code

From: Hans de Goede <hdegoede@redhat.com>

Improved pac207 decompression code to also support higher compression
modes of the pac207, which enables us to use higher framerates.
Many many thanks to Bertrik Sikken for figuring the decompression out!

Priority: normal

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 37 insertions, 20 deletions

diff --git a/v4l2-apps/libv4l/libv4lconvert/pac207.c b/v4l2-apps/libv4l/libv4lconvert/pac207.c
index 97ef4ebc0..a81d5d511 100644
--- a/v4l2-apps/libv4l/libv4lconvert/pac207.c
+++ b/v4l2-apps/libv4l/libv4lconvert/pac207.c
@@ -52,35 +52,35 @@ static void init_pixart_decoder(void)
 	    len = 2;
 	} else if ((i & 0xC0) == 0x40) {
 	    /* code 01 */
-	    val = -5;
+	    val = -1;
 	    len = 2;
 	} else if ((i & 0xC0) == 0x80) {
 	    /* code 10 */
-	    val = +5;
+	    val = +1;
 	    len = 2;
 	} else if ((i & 0xF0) == 0xC0) {
 	    /* code 1100 */
-	    val = -10;
+	    val = -2;
 	    len = 4;
 	} else if ((i & 0xF0) == 0xD0) {
 	    /* code 1101 */
-	    val = +10;
+	    val = +2;
 	    len = 4;
 	} else if ((i & 0xF8) == 0xE0) {
 	    /* code 11100 */
-	    val = -15;
+	    val = -3;
 	    len = 5;
 	} else if ((i & 0xF8) == 0xE8) {
 	    /* code 11101 */
-	    val = +15;
+	    val = +3;
 	    len = 5;
 	} else if ((i & 0xFC) == 0xF0) {
 	    /* code 111100 */
-	    val = -20;
+	    val = -4;
 	    len = 6;
 	} else if ((i & 0xFC) == 0xF4) {
 	    /* code 111101 */
-	    val = +20;
+	    val = +4;
 	    len = 6;
 	} else if ((i & 0xF8) == 0xF8) {
 	    /* code 11111xxxxxx */
@@ -109,7 +109,8 @@ static inline unsigned short getShort(const unsigned char *pt)
 }
 
 static int
-pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width)
+pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width,
+    int step_size, int abs_bits)
 {
     int col;
     int val;
@@ -135,11 +136,11 @@ pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width)
 	if (table[code].is_abs) {
 	    /* absolute value: get 6 more bits */
 	    code = getByte(inp, bitpos);
-	    bitpos += 6;
-	    *outp++ = code & 0xFC;
+	    bitpos += abs_bits;
+	    *outp++ = code & ~(0xff >> abs_bits);
 	} else {
 	    /* relative to left pixel */
-	    val = outp[-2] + table[code].val;
+	    val = outp[-2] + table[code].val * step_size;
 	    *outp++ = CLIP(val);
 	}
     }
@@ -148,18 +149,24 @@ pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width)
     return 2 * ((bitpos + 15) / 16);
 }
 
-void v4lconvert_decode_pac207(const unsigned char *inp, unsigned char *outp,
+int v4lconvert_decode_pac207(struct v4lconvert_data *data,
+  const unsigned char *inp, int src_size, unsigned char *outp,
   int width, int height)
 {
 /* we should received a whole frame with header and EOL marker
 in myframe->data and return a GBRG pattern in frame->tmpbuffer
 remove the header then copy line by line EOL is set with 0x0f 0xf0 marker
 or 0x1e 0xe1 for compressed line*/
+    const unsigned char *end = inp + src_size;
     unsigned short word;
     int row;
 
     /* iterate over all rows */
     for (row = 0; row < height; row++) {
+	if ((inp + 2) > end) {
+	    V4LCONVERT_ERR("incomplete pac207 frame\n");
+	    return -1;
+	}
 	word = getShort(inp);
 	switch (word) {
 	case 0x0FF0:
@@ -167,21 +174,31 @@ or 0x1e 0xe1 for compressed line*/
 	    inp += (2 + width);
 	    break;
 	case 0x1EE1:
-	    inp += pac_decompress_row(inp, outp, width);
+	    inp += pac_decompress_row(inp, outp, width, 5, 6);
+	    break;
+
+	case 0x2DD2:
+	    inp += pac_decompress_row(inp, outp, width, 9, 5);
 	    break;
 
-	case 0x2DD2: /* prefix for "stronger" compressed lines, currently the
-			kernel driver programs the cam so that we should not
-			get any of these */
+	case 0x3CC3:
+	    inp += pac_decompress_row(inp, outp, width, 17, 4);
+	    break;
+
+	case 0x4BB4:
+	    /* skip or copy line? */
+	    memcpy(outp, outp - 2 * width, width);
+	    inp += 2;
+	    break;
 
 	default: /* corrupt frame */
-	    /* FIXME add error reporting */
-	    return;
+	    V4LCONVERT_ERR("unknown pac207 row header: 0x%04x\n", (int)word);
+	    return -1;
 	}
 	outp += width;
     }
 
-    return;
+    return 0;
 }